基于统计信道信息的平流层大规模MIMO多用户系统关键技术研究

Traditional bottlenecks in stratospheric communications such as spectrum scarcity, sidelobe interference, cell overlap and user tracking due to the increase of user access can be addressed by introducing the massive MIMO technique, which can significantly improve the spectrum efficiency and raise the link reliability. However, the massive MIMO technique also brings the drawback such as high implementation complexity, high hardware and signaling overhead in downlink training when directly applied to stratospheric multiuser systems. Towards this end, this study investigates the stratospheric massive MIMO multiuser system with respect to channel modeling, two-stage precoding and interference mitigation. We first formulate the correlation model and derive channel statistical information (e.g., correlation matrix) based on the propagation characteristics in stratosphere. In addition, we use various mathematical tools such as the stochastic matrix and the optimization theory to analyze the channel capacity in stratospheric massive multiuser MIMO systems. Secondly, based on the knowledge of user channel correlation, a two-stage precoding algorithm is derived to effectively reduce the computational complexity. As another outcome of our study, we apply the multiuser correlation matrix to investigate interference mitigation algorithms, which aim at presenting a viable propagation strategy with high data rates and low complexity.

近年来，平流层通信因其覆盖广、配置灵活、传输质量高等优势成为业界的研究热点，但由于用户接入量大，平流层通信存在频谱紧张，旁瓣干扰等问题。大规模MIMO技术的引入可以有效改善上述问题，提高平流层通信的频谱效率。但是，将大规模MIMO技术直接应用于平流层系统，会导致抗干扰算法对导频敏感、算法复杂度高、硬件开销大等问题。本项目将在信道建模，双层预编码，和干扰抑制等方面开展平流层大规模MIMO多用户系统的研究。首先依据平流层的传播特点，建立平流层大规模MIMO信道模型，得到信道统计状态信息，并采用随机矩阵和优化理论等数学工具分析平流层大规模MIMO多用户系统的信道容量；其次，根据以用户信道相关性为基础的分组方案，设计多用户FDD系统的双层预编码算法有效降低算法的复杂度；最后利用多用户间的相关性矩阵，进行干扰抑制算法研究，提出高速率、低复杂度可实现的平流层大规模MIMO多用户接入系统传输方案。

本课题对基于统计信道信息的平流层大规模MIMO多用户系统进行了研究，主要包括平流层多天线系统的信道建模、波束成形系统的性能分析、无线信道的容量分析、双层预编码算法以及干扰抑制等。通过研究，我们获得了多项符合课题目标的创新成果，主要包括 HAP-MIMO 多用户信道建模和基于散射体动态演进的 HAP-MIMO 信道建模、基于静态散射体和动态散射体的 HAP-MIMO 信道建模、机会波束成型-用户分组联合优化方案和基于多用户间的相关性干扰矩阵的干扰抑制算法等。在课题研究中，课题组成员在IEEE Trans Vehicular Tech、IEEE Trans Comm、IEEE Comm Letters、IEEE Wireless Comm Letters、电子学报、通信学报等国内外权威刊物以及ISCAS、WCSP、WPMC等知名会议上发表论文共35篇，申请并公开发明专利8项，其中授权7项，培养博士生3名，硕士生9名。

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